(a) Field of the Invention
The present invention relates to a balloon for medical tubes and a medical tube equipped with such a balloon. More specifically, the present invention pertains to a balloon for medical tubes, which has variable bendability, which can impart, to a medical tube to be inserted into a living body for examinations and/or treatments, a direction-selecting function (the ability to select the course or direction of the tip of the medical tube) due to the variable or arbitrary bendability of the balloon or can impart, to the medical tube, a function of separating tissues by the variable bending motions of the balloon, while making the most use of the difference in the partial stretchability of the balloon induced when a pressurized fluid is injected therein, as well as a medical tube equipped with such a balloon.
(b) Description of the Prior Art
Operations performed in the past requiring severe operative invasion has gradually been superseded by the operative techniques with less operative invasion. For instance, there have spectacularly been spread widely therapeutic methods with minimum invasion therapy (MIT), mainly based on techniques which make use of catheters and endoscopes, such as PTCA, PTA and stent techniques, atelectomy, embolization and operations performed under an endoscope.
In particular, in the field of the catheter techniques, there have been developed a variety of balloon-catheters in order to, for instance, supply a medical fluid or an infusion solution to a specific site in a body cavity such as a blood vessel, a digestive tract, a uterine tube or a ureter, or to expand a site with a stenosis by the expansive force of a balloon.
However, a higher operative technique will require the development of a catheter whose tip portion has an ability to select its course of advancement by the bending of the same. In respect of the bending mechanism of the tip of a catheter, various structures have been proposed, but they are all complicated and the diameter of the catheters would inevitably be increased.
In addition, a catheter has conventionally been used only for the body cavities, except for a part of operations performed under endoscopes. However, there has been desired for the development of a catheter technique which is not limited only to the transluminal approach techniques which make use of biological tracts and/or cavities such as blood vessels, as the area of catheter application is widely expanded.
A cavity should be formed within a variety of tissues by a less frictional means to treat a target site by letting a catheter arrive at a desired site from the exterior of a biological tract or cavity, unlike the technique which makes use of the biological tract or cavity. To this end, tissues should often be separated over a wide area. After the catheter arrives at the desired portion, various tools may be adapted to carry out diagnosis and/or treatments through the use of the multiple lumens of the catheter.
As a method for separating tissues, the tip of a catheter may continuously be deformed and moved after the catheter arrives at the desired site on the tissue to be separated. Various structures have been proposed, as the bending mechanisms of the tip of the catheter, but all of them are very complicated and the diameter of the catheters would inevitably be increased. Moreover, there has not yet been developed any multifunctional catheter designed from the viewpoint of the non-transluminal approach to the tissue separation from the outside of the biological tract or cavity.
The present invention has been developed to solve the foregoing various problems associated with the conventional techniques and accordingly, an object of the present invention is to provide a balloon for medical tubes, which has variable bendability, which can impart a direction-selecting function due to the variable bendability of the balloon to a medical tube inserted into a living body for examinations and/or treatments, while making the most use of the difference in partial stretchability of the balloon induced when a pressurized fluid is injected therein, which has a simple structure and whose diameter can substantially be reduced, as well as a medical tube equipped with such a balloon.
Another object of the present invention is to provide a medical tubular structure equipped with a balloon designed from the viewpoint of the non-transluminal approach to the tissue separation from the outside of the biological tract or cavity, which thus has a function for separating biological tissues by the variable ability of the balloon to undergo bending motions, which has a simple structure and whose diameter can be reduced.
The inventors of this invention have conducted various studies to achieve the aforementioned objects and have found that variable bending ability can be imparted to a balloon and a direction-selecting function can thus be imparted thereto. In other words, a low stretchable section is partially formed on a cylindrical balloon along its circumferential direction by a cross-linking treatment to thus ensure a partial difference in the stretchability of the balloon. Accordingly, the balloon can expand to a large extent on the side of the high stretchable section, while the balloon on the side of the low stretchable section can expand to a lesser extent, when a pressurized fluid is injected therein. Thus, the balloon undergoes bending towards the side of the low stretchable section and the degree of the bending can be controlled by appropriately adjusting the pressure of the pressurized fluid. Accordingly, the inventors have completed an aspect of the present invention on the basis of the foregoing findings.
Alternatively, the inventors have also found the following. A cylindrical balloon is partially subjected to a cross-linking treatment to thus form at least two low stretchable sections over less than a half of the circumferential region on the cylindrical balloon, which partially extends in the axial direction of the balloon, these sections having low stretchability are arranged in such a manner that the positions thereof are deviated from one another in the axial direction of the balloon, preferably these sections substantially do not overlap with each other in the axial direction of the balloon, and they are arranged in the opposite circumferential directions of the balloon. Thus, the balloon can expand to a large extent on the side of the high stretchable section, while the balloon on the side of the low stretchable section can expand to a lesser extent, when a pressurized fluid is injected therein. Accordingly, the balloon undergoes bending in an S-shaped form, towards the side of the low stretchable section and the degree of the bending can be controlled by appropriately adjusting the pressure of the pressurized fluid. Accordingly, an ability of variable bending motions can be imparted to the balloon by applying a pulsative pressure of a pressurized fluid to the balloon and a tissue-separating function can thus be imparted thereto. Accordingly, the inventors have likewise completed another aspect of the present invention.
According to an aspect of the present invention, there is provided a cylindrical balloon for medical tubes, which has an ability to bend and which comprises a section having low stretchability (low stretchable section) partially formed, by a cross-linking treatment, on the balloon along the circumferential direction thereof.
In the balloon for medical tubes according to preferred embodiment of the present invention, the low stretchable section which is formed by a partial cross-linking treatment extends, over less than a half of the circumferential region on the cylindrical balloon, along the axial direction thereof; or a first low stretchable section which is formed by a partial cross-linking treatment partially extends, over less than a half of the circumferential region on the cylindrical balloon, along the axial direction thereof, while a second low stretchable section which is formed by a partial cross-linking treatment partially extends, over less than a half of the circumferential region on the cylindrical balloon, along the axial direction thereof, and the first and second low stretchable sections are circumferentially arranged in opposite directions of the balloon and are also arranged in such a manner that the positions thereof are deviated from one another in the axial direction of the balloon. However, the arrangement of these low stretchable sections is not limited to the foregoing embodiments or patterns. For instance, the sections may helically extend in the axial direction of the balloon or extend at an angle with respect to the axial direction of the balloon, or further at least three such sections may be arranged alternately and oppositely along the circumferential direction of the balloon.
According to another aspect of the present invention, there is also provided a medical tube equipped with a balloon, which comprises:
a shaft tube for being inserted into a living body;
a cylindrical balloon liquid-tightly connected to the shaft tube at the periphery of the tip thereof;
a first lumen which is provided within the shaft tube and communicates with the interior of the balloon; and
at least one second lumen which is formed within the shaft tube and is opened at the tip thereof;
wherein the cylindrical balloon comprises a low stretchable section which is partially formed on the circumferential region on the balloon by a cross-linking treatment.
In this respect, the foregoing cylindrical balloon used comprises a first low stretchable section, which is formed by a partial cross-linking treatment and which partially extends, over less than a half of the circumferential region on the balloon, along the axial direction thereof; and a second low stretchable section, which is formed by a partial cross-linking treatment and which partially extends, over less than a half of the circumferential region on the cylindrical balloon, along the axial direction of the balloon; the first and second sections being circumferentially arranged in opposite directions of the balloon and arranged in such a manner that the positions thereof are deviated from one another (or they are not in line with each other) in the axial direction of the balloon. The use of the cylindrical balloon can ensure the achievement of a sufficient tissue-separating function due to the variable bending motions of the balloon.
According to a further aspect of the present invention, there is also provided a medical tube equipped with a balloon, which comprises:
a shaft tube for being inserted into a living body;
a cylindrical balloon, one end of which is liquid-tightly connected to the shaft tube at the tip thereof;
a long tool for medical treatments or for diagnoses, whose tip portion is liquid-tightly connected to the other end of the balloon directly or indirectly; and
a first lumen which is formed within the shaft tube and communicates with the interior of the balloon so that a liquid can pass through the balloon and which accommodates the long tool for medical treatments or for diagnoses;
or a medical tube equipped with a balloon, which comprises:
a shaft tube for being inserted into a living body;
a cylindrical balloon, one end of which is liquid-tightly connected to the shaft tube at the tip thereof;
a long tool for medical treatments or for diagnoses, whose tip portion is liquid-tightly connected to the other end of the balloon directly or indirectly;
a first lumen which is formed within the shaft tube and communicates with the interior of the balloon so that a liquid can pass through the balloon and which accommodates the long tool for medical treatments or for diagnoses; and
at least one second lumen which is formed within the shaft tube and is opened at the periphery of the tip thereof; wherein the cylindrical balloon comprises an area having low extensibility which is partially formed on the peripheral portion of the balloon by a cross-linking treatment.